Mountain View, CA—Stendra (avanafil) is the latest of the phosphodiesterase type 5 inhibitors to be approved by the FDA. It helps boost blood flow to the penis and joins Viagra, Cialis, and Levitra in the marketplace.

The FDA approval document says Stendra, marketed by Mountain View, California-based VIVUS Inc., is fast-acting and is designed to be taken 30 minutes before sexual activity and at the lowest effective dose.

"This approval expands the available treatment options to men experiencing erectile dysfunction, and enables patients, in consultation with their doctor, to choose the most appropriate treatment for their needs," Dr. Victoria Kusiak, deputy director of the Office of Drug Evaluation III in the FDA's Center for Drug Evaluation and Research,
said in a statement.

According to the drug label, the starting dose is 100 mg and can be used on an as-needed basis but not more than once a day. The dose may be increased to 200 mg or decreased to 50 mg based on efficacy and/or tolerability, according to the FDA, which recommends using the lowest dose that provides benefit.

Stendra is the first of a new generation of PDE5 inhibitors and was developed to meet the need for more options in ED treatment,
according to VIVUS. "Patients and treating physicians continue to report significant dissatisfaction with current treatments of ED," said Peter Tam, the company's president. "We believe that the PDE5 selectivity and absorption profile of Stendra make it an important new treatment option for many men with erectile dysfunction."

The safety and efficacy of Stendra were established in three double-blind, placebo-controlled clinical studies, with 1,267 patients randomly assigned to take Stendra for up to 12 weeks at doses of 50 mg, 100 mg, or 200 mg, or a placebo as needed about 30 minutes before sexual activity.

As with other drugs in this class, FDA said that Stendra should not be taken by men who use nitrates because of the threat of a sudden drop in blood pressure.

The ED drugs sometimes can cause color vision changes and, rarely, sudden loss of vision in one or both eyes, the agency also warned. In some cases, hearing loss also has been reported.

"Patients who experience a sudden loss of vision or hearing should stop taking PDE5 inhibitors, including Stendra, and call a doctor right away," the FDA said.

The most common side effects reported with Stendra include headache, redness of the face and other areas, nasal congestion, cold-like symptoms, and back pain.

Stendra also shares another warning with the other drugs in the class. Men who take it are cautioned about an erection that lasts more than 4 hours and won't go away. "If this happens, patients should seek immediate medical care," the FDA said